Hub assembly

Abstract

This hub assembly 41 includes a bearing device 1 for wheel and a constant velocity universal joint 21 which are mutually joined through a screw member 44 having external thread parts 42, 43 at both ends. When being inserted into a through-hole 16 axially penetrating an inner member 12, the screw member 44 has the external thread part 42 on one end that is screwed into an internal thread hole 46 at a bottom part 27 of an outer joint member 22, and the external thread part 43 on the other end, to which a nut 45 is attached so as to clamp the inner member 12 by the nut 45 and the outer joint member 22.

Description

Hub Assembly

[0001] The present invention relates to a hub assembly, and more particularly to a hub assembly for a wheel bearing device and a constant velocity universal joint.

[0002] For example, a power transmission device that transmits engine power to wheels of an automobile or the like must transmit power from the engine to the wheels, and must also accommodate angular displacement for turning the vehicle, in addition to angular and axial displacement due to bouncing of the vehicle while driving. Therefore, a drive shaft of an automobile or the like generally has a sliding-type constant velocity joint on the differential side (inboard side) that can accommodate angular and axial displacement, and a fixed-type constant velocity joint on the drive wheel side (outboard side) that allows for a large operating angle, with both constant velocity joints connected by a shaft. Furthermore, the constant velocity joint on the drive wheel side (fixed-type constant velocity joint) is connected to a wheel bearing device that rotatably supports the drive wheel.

[0003] The power transmission structure between the wheel bearing device and the constant velocity universal joint described above generally employs a spline fit between the outer ring stem of the constant velocity universal joint and the hub ring of the wheel bearing device (see, for example, Patent Document 1), but recently a structure has also been proposed in which face spline portions that fit together in the axial direction are formed on the axial end face of the hub ring and the axial end face of the outer ring of the constant velocity universal joint that abuts against the axial end face, and the teeth that make up these face spline portions fit together (interlock) to transmit power between the wheel bearing device and the constant velocity universal joint. In this case, the hub ring and outer ring are fixed to each other by, for example, threading the tip of a bolt inserted into the inner periphery of the hub ring into an internally threaded hole in the bottom of the outer ring and tightening the hub ring with the bolt (see, for example, Patent Document 2).

[0004] In the case of a conventional power transmission structure (a spline fit structure between the outer ring stem and the hub wheel), when high torque is input from the vehicle side, deformation such as torsion can cause the axial end face of the hub wheel to slip against the axial end face of the outer ring of the constant velocity universal joint, which are butted together in the axial direction, which can result in the generation of abnormal noise and vibration.In contrast, if a spline fit structure is used at the axial butt portion of the outer ring and hub wheel, the above-mentioned slippage is prevented even if deformation such as torsion described above occurs, making it possible to suppress the generation of abnormal noise and vibration.

[0005] JP 2022-129698 A Patent No. 5556509 A

[0006] On the other hand, the spline fitting structure related to the axial butt portion described below has the problem of being less workable during the vehicle assembly process than conventional spline fitting structures. That is, when a wheel bearing device and a constant velocity universal joint are connected to transmit power using a conventional spline fitting structure, the wheel bearing device including the hub wheel is positioned and held by the stem portion of the outer ring by spline fitting the stem portion of the outer ring. This allows the next step of installing a nut without worrying about the constant velocity universal joint falling off the hub wheel (wheel bearing device). In other words, the worker can install a nut on the male thread portion at the end of the stem portion and tighten and secure the hub wheel without having to support the constant velocity universal joint with his or her hand.

[0007] In contrast, when a spline fitting structure for the axial butt portion is adopted, even after the face spline portions on the axial end face of the hub wheel and the axial end face of the outer ring are aligned and fitted, the worker must continue to support the constant velocity universal joint by hand while inserting the connecting bolt into the hole in the hub wheel from the axially outer side (inboard side), screwing the male threads of the bolt into the female threaded hole on the bottom of the outer ring, and tightening the hub wheel. Therefore, when the latter structure is adopted, the increased workload can lead to a decrease in workability.

[0008] Furthermore, the above-mentioned assembly process requires the supply of a constant velocity universal joint in a fully assembled state. Therefore, when abutting the axial direction (when engaging the splines), the female threaded hole at the bottom of the outer ring must be covered with a removable lid or the like to prevent the grease sealed inside the constant velocity universal joint from leaking out, and the lid must be removed when screwing the bolt into the female threaded hole. Therefore, this also increases the amount of work required and may lead to reduced workability.

[0009] In view of the above circumstances, the technical problem to be solved in this specification is to provide a hub assembly of a wheel bearing device and a constant velocity universal joint that is capable of transmitting power via a spline fitting structure at the axial butt joint without reducing workability.

[0010] The above-mentioned problems are solved by a hub assembly of a wheel bearing device and a constant velocity universal joint according to the present invention. That is, this hub assembly is a hub assembly of a wheel bearing device and a constant velocity universal joint, characterized in that a first face spline portion provided on an axial end surface of an inner member of the wheel bearing device is fitted with a second face spline portion provided on an axial end surface of an outer joint member of the constant velocity universal joint facing the axial end surface of the inner member, thereby connecting the inner member and the outer joint member together, a threaded member having male threads on both ends is inserted into a through hole passing axially through the inner member, one male thread portion is screwed into an internally threaded hole provided in a bottom portion of the outer joint member, and a nut is attached to the other male thread portion so as to sandwich and tighten the inner member between the nut and the outer joint member.

[0011] As described above, the hub assembly according to the present invention includes a threaded member having male threads at both ends, and a detachable nut attached to the male threads. With one male threaded portion threaded into the outer joint member, the nut is attached to the other male threaded portion, allowing the inner member to be clamped and fastened between the nut and the outer joint member. With this configuration, the constant velocity universal joint and the wheel bearing device can be butted (spline-fitted) with the threaded member fixed to the outer joint member inserted into the through-hole of the inner member. This allows the constant velocity universal joint to be butted and the subsequent nut installation work to be performed in a cantilevered state, eliminating the need for the worker to support the constant velocity universal joint by hand during the butt-fitting work and improving workability. Furthermore, since the threaded member is already fixed to the outer joint member upon completion of the axial butt-fitting work, the conventional process of fixing a bolt to the outer joint member after the butt-fitting work can be omitted. In addition, because the butt-jointing operation can be performed with the threaded member fixed to the outer joint member, the time and effort of removing a cover or the like that was covering the female threaded hole of the outer joint member after the butt-jointing operation is also unnecessary. As described above, the hub assembly according to the present invention improves the workability during the assembly process of the hub assembly and reduces the work involved, so that it is possible to improve the workability of the assembly process overall, even while providing a configuration in which a face spline portion is provided at the axial butt portion.

[0012] In addition, in the hub assembly according to the present invention, the axial central portion of the screw member may be formed with a larger diameter than the male thread portions located at both ends of the screw member, and the axial central portion may be inserted into the through hole in a loose fit.

[0013] By configuring the threaded member in this manner, the gap between the inner member and the threaded member can be set small, which improves the ability to hold the constant velocity universal joint in a cantilevered state when butting together, thereby enabling further improvements in workability.

[0014] In the hub assembly according to the present invention, a first flange having a larger diameter than one of the male threaded portions may be provided adjacent to the center end of one of the male threaded portions.

[0015] By providing the first flange adjacent to one of the male threaded portions in this manner, for example, the end face of the flange can be brought into contact with the bottom of the outer joint member, thereby functioning as a positioning device when screwing one of the male threaded portions into the female threaded hole in the bottom. It goes without saying that the maximum outer diameter of the first flange should be set smaller than the minimum inner diameter of the through hole of the inner member.

[0016] In the hub assembly according to the present invention, a second flange having a larger diameter than the other male threaded portion may be provided adjacent to the center end of the other male threaded portion.

[0017] By providing the second flange adjacent to the other male threaded portion in this way, the flange can contribute to improving the holding ability of the constant velocity universal joint in a cantilevered state when butting together. Also, by shaping the threaded member as described below and making the other male threaded portion usable as one of the male threaded portions, the second flange can function as a positioning member when screwing the other male threaded portion into the female threaded hole of the outer joint member.

[0018] In the hub assembly according to the present invention, the screw member may be symmetrical with respect to the axial center position.

[0019] By configuring the screw member in this manner, workers can handle the screw member without having to worry about its orientation, which reduces work errors such as incorrect installation and makes it possible to further improve workability.

[0020] In the hub assembly according to the present invention, the screw member may have a male thread portion along its entire axial length.

[0021] By configuring the screw member in this way, not only can the worker handle the screw member without having to worry about the orientation as described above, but it can also be procured at low cost, which makes it possible to further reduce production costs, including labor costs.

[0022] In the hub assembly according to the present invention, a protrusion may be provided on the bottom of the outer joint member, the protrusion having a shape that causes the bottom to protrude toward its outer bottom surface, and a female threaded hole may be formed so as to axially penetrate the bottom, including the protrusion.

[0023] By providing a protrusion on the bottom of the outer joint member and providing a female threaded hole that penetrates the bottom including the protrusion, the axial dimension of the female threaded hole can be increased, thereby ensuring the fixing strength between the threaded member and the outer joint member even in a limited space. Furthermore, if the protrusion has a shape in which the bottom protrudes toward the outer bottom surface, there is no risk of the protrusion interfering with the surrounding area.

[0024] Furthermore, in the hub assembly according to the present invention, when the above-mentioned protrusion is provided, the protrusion may be fitted into one end opening of the through hole.

[0025] By defining the shape of the protrusion in this way, the protrusion can function as a guide when butting together, and the constant velocity universal joint can be held in a cantilevered state more easily, thereby enabling the above-mentioned series of operations to be carried out smoothly.

[0026] The above-mentioned object can also be achieved by a method for assembling a hub assembly according to the present invention. That is, this assembling method is a method for assembling a hub assembly of a wheel bearing device and a constant velocity universal joint, and is characterized in that the male threaded portion provided on one end of the threaded member is fastened to the female threaded hole provided in a bottom portion of the outer joint member of the constant velocity universal joint, and then, with the threaded member inserted into a through hole that axially passes through the inner member of the wheel bearing device, a first face spline portion provided on an axial end surface of the inner member of the wheel bearing device is fitted with a second face spline portion provided on an axial end surface of the outer joint member of the constant velocity universal joint that faces the axial end surface of the inner member, thereby connecting the inner member and the outer joint member to each other, and then a nut is attached to the male threaded portion provided on the other end of the threaded member, and the inner member is sandwiched and tightened between the nut and the outer joint member.

[0027] According to the assembly method of the present invention, as with the hub assembly of the present invention, the constant velocity universal joint and the wheel bearing device can be butted together (spline-fitted) with the threaded member fixed to the outer joint member inserted into the through-hole of the inner member. This allows the constant velocity universal joint to be cantilevered while the butt-fitting operation and the subsequent nut installation operation are performed, eliminating the need for the worker to manually support the constant velocity universal joint during the operation and improving workability. Furthermore, since the threaded member is already fixed to the outer joint member upon completion of the axial butt-fitting operation, the conventional process of fixing a bolt to the outer joint member after the butt-fitting operation can be omitted. Furthermore, since the butt-fitting operation can be performed with the threaded member fixed to the outer joint member, the time required to remove a cover or the like covering the female threaded hole of the outer joint member after the butt-fitting operation is also eliminated. As described above, the hub assembly assembling method of the present invention improves workability during the hub assembly process and reduces the amount of work required, so even though a face spline portion is provided at the axial butt portion, it is possible to improve workability in the assembly process overall.

[0028] As described above, according to the present invention, it is possible to provide a hub assembly of a wheel bearing device and a constant velocity universal joint that is capable of transmitting power through a spline fitting structure at the axial butt joint without reducing workability.

[0029] Fig. 1 is a cross-sectional view of a hub assembly of a wheel bearing device and a constant velocity universal joint according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view for explaining the assembly process of the hub assembly shown in Fig. 1, showing a state just before the constant velocity universal joint is butted against the wheel bearing device. Fig. 3 is a cross-sectional view of a hub assembly of a wheel bearing device and a constant velocity universal joint according to a second embodiment of the present invention. Fig. 4 is a cross-sectional view of a hub assembly of a wheel bearing device and a constant velocity universal joint according to a third embodiment of the present invention.

[0030] A first embodiment of the present invention will now be described with reference to the drawings. First, the basic configurations of a wheel bearing device and a constant velocity universal joint will be described, followed by a description of a spline fitting structure, and then a description of a connection structure via a screw member.

[0031] FIG. 1 shows a hub assembly 41 including a wheel bearing device 1 and a constant velocity universal joint 21. In this embodiment, the wheel bearing device 1 is formed as a unit and is detachably attached to the constant velocity universal joint 21, which is also formed as a unit. The wheel bearing device 1 mainly comprises an outer member 2, a hub ring 3, an inner ring 4, balls 5 as rolling elements, and a cage 6. Double-row outer raceways 7, 7 are formed on the inner periphery of the outer member 2, and a vehicle body mounting flange 8 for mounting to a knuckle (not shown) of the vehicle body is integrally formed on the outer periphery. The hub ring 3 has a wheel mounting flange 9 for mounting a wheel (not shown) integrally formed at one end thereof, and an inner raceway 10 facing one of the double-row outer raceways 7, 7 of the outer member 2 on the outer periphery, and a cylindrical small-diameter step 11 extending axially from the inner raceway 10. The inner ring 4 is press-fitted into this small diameter step 11, and an inner raceway surface 10 is formed on the outer periphery of the inner ring 4, opposing the other of the double row outer raceway surfaces 7, 7 of the outer member 2. In this case, the hub ring 3 and the inner ring 4 constitute an inner member 12. A plurality of balls 5, 5 are incorporated so as to roll freely between the double row outer raceway surfaces 7, 7 of the outer member 2 and the double row inner raceway surfaces 10, 10 of the inner member 12, and each ball 5 is housed in a cage 6. The inner ring 4 is fixed in the axial direction by a crimped portion 13 formed by plastically deforming the axial end of the small diameter step 11 of the hub ring 3 radially outward. In this case, a first face spline portion 14 is formed on the axial end face 13a of the crimped portion 13.

[0032] On the other hand, the constant velocity universal joint 21 mainly comprises an outer joint member 22, an inner joint member 23, a cage 24, and torque transmission balls 25. The outer joint member 22 is made up of a cup portion 26 and a bottom portion 27 formed integrally with the cup portion 26. In this case, a second face spline portion 29 is formed on an axial end surface 28a of a shoulder portion 28 corresponding to the radially outer region of the bottom portion 27. This face spline portion 29 is brought into axial contact with a first face spline portion 14 formed on the axial end surface 13a of the crimped portion 13 of the hub wheel 3, thereby resulting in a mutually meshed state, whereby rotational torque from the shaft 31 can be transmitted to the wheel mounting flange 9 via the constant velocity universal joint 21 and the hub wheel 3.

[0033] Here, the first face spline portion 14 is formed by circumferentially arranging a plurality of teeth 15 as ridges. In this embodiment, each tooth 15 extends along the radial direction of the first face spline portion 14 (and thus the hub wheel 3), and its cross-sectional shape is the same on any radial cross section. The distance between adjacent teeth 15 in the circumferential direction (i.e., the circumferential dimension of the tooth root) increases radially outward from the rotation center axis. To give an example of the specifications of the first face spline portion 14, when used in a passenger vehicle including a four-wheel drive vehicle, the outer diameter of the first face spline portion 14 is approximately 45 to 70 mm, the module of the teeth 15 is approximately 1 to 3 mm, and the pressure angle is approximately 20 to 30°. The second face spline portion 29 provided on the constant velocity universal joint 21 side and the plurality of teeth 30 constituting this face spline portion 29 also have the same shape and specifications. Of course, the above configuration and specifications are merely an example, and the configuration and specifications can be set arbitrarily as long as they can function as the face spline portions 14, 29 in the fitted state.

[0034] These face spline portions 14, 29 can be formed by various methods. For example, the first face spline portion 14 provided on the wheel bearing device 1 side can be formed simultaneously with the crimped portion 13 by using a rotary mode oscillation molding machine (not shown). Of course, the method for forming the first face spline portion 14 is not limited to the rotary mode oscillation molding described above, and other oscillation molding methods or plastic processing can also be used. Furthermore, the first face spline portion 14 may be formed simultaneously with the crimped portion 13, or may be formed after the crimped portion 13 is formed.

[0035] Furthermore, although not shown, the second face spline portion 29 provided on the constant velocity universal joint 21 side can be formed on the shoulder portion 28 of the bottom portion 27 at the same time as the outer joint member 22 is formed by plastic working. Of course, it is also possible to form the second face spline portion 29 on the shoulder portion 28 of the bottom portion 27 by plastic working after the outer joint member 22 is manufactured. Alternatively, the second face spline portion 29 can be formed by an appropriate means other than plastic working (for example, cutting under NC control).

[0036] Next, we will explain the structure for connecting and fixing the wheel bearing device 1 and the constant velocity universal joint 21. This connecting and fixing structure has a screw member 44 having male threads 42, 43 at both ends, a nut 45, and a female threaded hole 46 provided in a central region of the bottom 27 of the outer joint member 22.

[0037] The screw member 44 is inserted into the through hole 16 that axially passes through the hub wheel 3 of the inner member 12, with one male threaded portion 42 screwed into a female threaded hole 46 provided in the bottom portion 27 of the outer joint member 22, and a nut 45 attached to the other male threaded portion 43.

[0038] The nut 45, when attached while being threaded onto the other male thread portion 43, abuts against the hub wheel 3 in the axial direction, and can be tightened by sandwiching the hub wheel 3 between the outer joint member 22 in the axial direction, with the outer joint member 22 and the hub wheel 3 connected so as to be able to transmit power by the engagement of the face spline portions 14, 29. Therefore, in this embodiment, the axial dimensions of the male thread portions 42, 43 and the axial dimension of the screw member 44 are set to appropriate sizes so that the hub wheel 3 and the nut 45 abut in the axial direction when one male thread portion 42 is threaded into the female threaded hole 46 over its entire axial length and the nut 45 is threaded into the other male thread portion 43 up to an intermediate position in the axial direction.

[0039] In this case, the outer diameters of one male threaded portion 42 and the axial center portion 48 of the screw member 44 are both set to be smaller than the minimum inner diameter of the through hole 16 .

[0040] In this embodiment, the threaded member 44 is symmetrical with respect to the axial center position. That is, the threaded member 44 has a substantially constant outer diameter dimension over its entire axial length, and at least one male threaded portion 42 and the other male threaded portion 43 have positions, shapes, and dimensions that are symmetrical with respect to the axial center position of the threaded member 44. Therefore, the threaded member 44 can be used in a state opposite to the orientation shown in FIG. 1 , that is, the other male threaded portion 43 can be used as one male threaded portion 42, and one male threaded portion 42 can be used as the other male threaded portion 43.

[0041] In the present embodiment, a protrusion 47 is provided on the bottom portion 27 of the outer joint member 22. The protrusion 47 protrudes from the bottom portion 27 toward the outer bottom surface (the right side in FIG. 1 ). In this case, a female screw hole 46 is formed so as to axially penetrate the bottom portion 27, including the protrusion 47.

[0042] In this embodiment, the protrusion 47 has an outer surface shape that conforms to the inner surface of the other end opening side of the through hole 16. In Fig. 1, the inner surface of the other end opening side of the through hole 16 has a shape that increases in diameter toward the other end side (constant velocity universal joint 21 side), and the outer surface of the protrusion 47 has a shape that increases in diameter toward the other end side.

[0043] The hub assembly 41 having the above configuration is assembled, for example, in the following manner.

[0044] First, the wheel bearing device 1 and the constant velocity universal joint 21 are prepared, with the exception of the connecting and fixing structure including the screw member 44, and are completely assembled (unitized). Then, one male threaded portion 42 of the screw member 44 is screwed into the female threaded hole 46 provided in the bottom portion 27 of the outer joint member 22 to a predetermined axial position, and then the wheel bearing device 1 and the constant velocity universal joint 21 are moved closer to each other in the axial direction, and the screw member 44 connected and fixed to the outer joint member 22 is inserted into the through hole 16 of the hub wheel 3 (see FIG. 2 ). Therefore, just before the first face spline portion 14 provided in the crimped portion 13 of the hub wheel 3 and the second face spline portion 29 provided in the shoulder portion 28 of the outer joint member 22 are butted in the axial direction, the abutment of the screw member 44 can minimize the risk of one of the constant velocity universal joint 21 and the wheel bearing device 1 being significantly tilted relative to the other and falling off.

[0045] Thereafter, the first face spline portion 14 and the second face spline portion 29 are butted together and fitted together with their circumferential positions aligned, thereby enabling rotational power to be transmitted between the wheel bearing device 1 and the constant velocity universal joint 21 via both face spline portions 14, 29.

[0046] After achieving spline fitting in this manner, the nut 45 is screwed onto the other male thread portion 43 of the screw member 44, and the nut 45 is pressed axially against the hub wheel 3, and the hub wheel 3 is clamped axially between the nut 45 and the outer joint member 22. This brings the outer joint member 22 and the hub wheel 3 into a connected and fixed state via the screw member 44 and the nut 45 (the state shown in FIG. 1), completing the assembly of the hub assembly 41 between the wheel bearing device 1 and the constant velocity universal joint 21.

[0047] As described above, the hub assembly 41 according to this embodiment is provided with a threaded member 44 having male threaded portions 42, 43 at both ends, a detachable nut 45 for the other male threaded portion 43, and a structure in which one male threaded portion 42 is threaded into the female threaded hole 46 of the outer joint member 22 and the nut 45 is threaded onto the other male threaded portion 43 allows the hub wheel 3 to be clamped in the axial direction between the nut 45 and the outer joint member 22 and fastened, so that the butt fitting operation (spline fitting operation) of the constant velocity universal joint 21 and the wheel bearing device 1 can be performed with the threaded member 44 fixed to the outer joint member 22 inserted into the through hole 16 of the hub wheel 3. This allows the butt fitting operation and the subsequent installation operation of the nut 45 to be performed with the constant velocity universal joint 21 supported in a cantilevered state, eliminating the need for the worker to support the constant velocity universal joint 21 with their hands during the above operation and improving workability. Furthermore, because the threaded members 44 are already fixed to the outer joint part 22 when the axial butt-fitting operation is completed, the conventional process of fixing bolts to the outer joint part 22 after the butt-fitting operation can be omitted. In addition, because the butt-fitting operation can be performed with the threaded members 44 fixed to the outer joint part 22, the effort of removing a cover or the like that covers the female threaded hole 46 of the outer joint part 22 after the butt-fitting operation is also unnecessary. As described above, the hub assembly 41 according to the present invention improves the workability during the assembly process of the hub assembly 41 and reduces the work effort itself, so it is possible to improve the workability of the assembly process overall, even though the face spline portions 14, 29 are provided at the axial butt portions (the crimped portion 13 and the shoulder portion 28).

[0048] Furthermore, in this embodiment, the protrusion 47 is provided and the female threaded hole 46 is provided penetrating the bottom 27 including the protrusion 47. This makes it possible to secure a large fixing area between the screw member 44 and the outer joint member 22 within a limited space, thereby enabling a strong connection and fixation.

[0049] In addition, the outer surface of the protrusion 47 is shaped to conform to the inner surface of the other end opening of the radially opposing through hole 16, thereby reducing the gap with the inner surface of the through hole 16 and improving the holding ability in a cantilevered state during the butting operation.

[0050] The above describes the first embodiment of the present invention, but the above-mentioned hub assembly of a wheel bearing device and a constant velocity universal joint and the assembly method thereof can also take other forms as long as they fall within the scope of the present invention.

[0051] For example, while the above embodiment illustrates a case where the threaded member 44 has a substantially constant outer diameter throughout its entire axial length, the threaded member according to the present invention can take other forms as well. Figure 3 shows a cross-sectional view of a hub assembly 41 according to one such example (a second embodiment of the present invention). As shown in Figure 3, in the hub assembly 41 according to this embodiment, the outer diameter of an axially central portion 48 of the threaded member 44 is larger than the outer diameters of the male threaded portions 42, 43 located at both ends of the threaded member 44, and the threaded member 44 is inserted into the through hole 16 of the hub wheel 3 so that the axially central portion 48 is a clearance fit with the through hole 16.

[0052] By providing a large diameter portion on the threaded member 44 in this way, the gap between the hub wheel 3 and the threaded member 44 can be set small. This improves the retention of the constant velocity universal joint 21 in a cantilevered state when butting together, making it possible to further improve workability. Of course, even if there is no clearance fit with the through hole 16 of the hub wheel 3, a configuration in which the axial center portion 48 is formed with a larger diameter than both end portions (external threaded portions 42, 43) is preferable because this can contribute to improving the retention of the constant velocity universal joint 21.

[0053] Figure 4 shows a cross-sectional view of a hub assembly 41 according to yet another example (third embodiment of the present invention). As shown in Figure 4, the hub assembly 41 according to this embodiment has a first flange 49, which is larger in diameter than one of the male threaded portions 42, and is provided adjacent to the central end of the one of the male threaded portions 42. In this embodiment, in addition to the first flange 49, a second flange 50, which is larger in diameter than the other male threaded portion 43, is provided adjacent to the central end of the other male threaded portion 43.

[0054] In this case, the axial end face of the first flange portion 49 is in surface contact with the outer bottom surface of the bottom portion 27 of the outer joint member 22 .

[0055] In this embodiment, the threaded member 44 is configured to be symmetrical with respect to the axial center position. That is, one male threaded portion 42 and the other male threaded portion 43 are formed to have the same shape and dimensions so as to be symmetrical with respect to the axial center position of the threaded member 44. Furthermore, the first flange portion 49 and the second flange portion 50 are formed to have the same shape and dimensions so as to be symmetrical with respect to the axial center position of the threaded member 44.

[0056] By providing the first flange 49 adjacent to one of the male threaded portions 42 in this manner, the one of the male threaded portions 42 can be screwed into a position where the axial end face of the first flange 49 abuts against the outer bottom surface of the bottom portion 27 of the outer joint member 22, and the first flange 49 can function as a positioning device when screwing the one of the male threaded portions 42 into the female threaded hole 46 of the bottom portion 27.

[0057] Furthermore, by providing the second flange 50 adjacent to the other male threaded portion 43, this flange 50 can improve the holding ability of the constant velocity universal joint 21 in a cantilevered state when butted. Furthermore, by forming the threaded member 44 symmetrically with respect to the axial center position as in this embodiment, the other male threaded portion 43 can also be used as one male threaded portion 42, so that the threaded member 44 can be attached to the outer joint member 22 without regard to the orientation of the threaded member 44, and workability can be further improved.

[0058] In the above embodiment, the male thread portions 42, 43 are provided at both ends of the screw member 44, but other configurations are also possible. For example, although not shown, it is also possible to provide a male thread portion over the entire axial length of the screw member 44.

[0059] Furthermore, in the above embodiment, an example has been given in which the protrusion 47 has an outer surface shape conforming to the inner surface of the other end opening of the through hole 16, but in this case, the protrusion 47 may be configured to fit into the other end opening of the through hole 16. That is, although not shown, the outer diameter of the protrusion 47 may be set so that the gap with the other end opening of the through hole 16 in the configuration shown in Fig. 1 is small enough to provide a clearance fit, for example. This further stabilizes the posture of the constant velocity universal joint 21 when butting together, making it possible to carry out each step more efficiently and easily.

[0060] In the above embodiment, the female threaded hole 46 is provided so as to penetrate the bottom portion 27 of the outer joint member 22, but it does not necessarily have to penetrate all the way through. In the case where the protrusion 47 is provided on the outer bottom surface side of the bottom portion 27 as shown in Fig. 1 etc., although not shown, the female threaded hole 46 may be provided so as to open on the tip side of the protrusion 47 and extend to a middle position in the thickness direction of the bottom portion 27 of the outer joint member 22 including the protrusion 47.

[0061] DESCRIPTION OF SYMBOLS 1 Wheel bearing device 2 Outer member 3 Hub ring 4 Inner ring 5 Ball 6 Cage 7 Outer raceway surface 8 Vehicle body mounting flange 9 Wheel mounting flange 10 Inner raceway surface 11 Small diameter step portion 12 Inner member 13 Crimping portion 13a Axial end face 14 First face spline portion 15 Teeth 16 Through hole 21 Constant velocity universal joint 22 Outer joint member 23 Inner joint member 24 Cage 25 Torque transmitting ball 26 Cup portion 27 Bottom portion 28 Shoulder portion 28a Axial end face 29 Second face spline portion 30 Teeth 31 Shaft 41 Hub assembly 42, 43 Male thread portion 44 Threaded member 45 Nut 46 Female thread hole 47 Projection portion 48 Axial center portion 49 First flange 50 Second flange

Claims

1. A hub assembly of a wheel bearing device and a constant velocity universal joint, wherein a first face spline portion provided on the axial end face of the inner member of the wheel bearing device and a second face spline portion provided on the axial end face of the outer joint member of the constant velocity universal joint that faces the axial end face of the inner member are fitted together, thereby connecting the inner member and the outer joint member, and a screw member having male threads on both ends is inserted into a through hole that passes axially through the inner member, with one of the male threads being screwed into a female threaded hole provided in the bottom of the outer joint member, and the nut is attached to the other male thread portion so that the inner member is sandwiched and tightened between the nut and the outer joint member.

2. A hub assembly of a wheel bearing device and a constant velocity universal joint as described in claim 1, wherein the axial center portion of the screw member is formed with a larger diameter than the male thread portions located at both ends of the screw member, and the axial center portion is inserted into the through hole in a loose fit state.

3. A hub assembly of a wheel bearing device and a constant velocity universal joint as described in claim 1, wherein a first flange portion having a larger diameter than said one male thread portion is provided adjacent to the central end of said one male thread portion.

4. A hub assembly of a wheel bearing device and a constant velocity universal joint as described in claim 3, wherein a second flange portion having a larger diameter than the other male thread portion is provided adjacent to the central end of the other male thread portion.

5. A hub assembly of a wheel bearing device and a constant velocity universal joint according to claim 1, wherein said screw members are symmetrical with respect to a central position in the axial direction.

6. A hub assembly of a wheel bearing device and a constant velocity universal joint according to claim 1, wherein said screw member has said male thread portion over its entire axial length.

7. A hub assembly of a wheel bearing device and the constant velocity universal joint as described in claim 1, wherein a protrusion is provided on the bottom of the outer joint member, the protrusion being shaped to protrude from the bottom surface of the bottom, and the female threaded hole is formed so as to axially penetrate the bottom, including the protrusion.

8. A hub assembly of a wheel bearing device and a constant velocity universal joint according to claim 7, wherein said protrusion is fitted into one end opening of said through hole.

9. A method for assembling a hub assembly of a wheel bearing device and a constant velocity universal joint, comprising: threading one male threaded portion of a screw member having male threaded portions at both ends into a female threaded hole provided in the bottom of the outer joint member of the constant velocity universal joint; inserting the screw member into a through hole that axially passes through the inner member of the wheel bearing device; engaging a first face spline portion provided on the axial end face of the inner member of the wheel bearing device with a second face spline portion provided on the axial end face of the outer joint member of the constant velocity universal joint that faces the axial end face of the inner member, thereby connecting the inner member and the outer joint member together; and then attaching a nut to the other male threaded portion provided on the other end of the screw member, and clamping and tightening the inner member between the nut and the outer joint member.

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